High-carbon steel wire rods can be used for producing products such as high-strength pre-stressed steel wire, steel strand, spring steel wire, steel rope and steel cord. The production of these products requires the high-carbon steel wire rod to be stretched for multiple times, with a stretching area reduction rate that maximally reaches 96%. Such a high stretching area reduction rate necessarily has high requirements for various aspects such as strength, plasticity, surface quality and purity of the high-carbon steel material.
Currently, the pre-stressed steel wires and steel strands on the domestic market are mainly 1860 MPa level products made of the raw material of SWRH82B high-carbon steel wire rod with a diameter of 11-13 mm and a strength of 1130-1200 MPa. There are also 1960 MPa level pre-stressed steel strands or even 2100 MPa level pre-stressed steel strands. In the steel manufacturing industry, it has always been a trend for research and development in this field to develop high-strength steel material, as the increase of steel material strength would reduce the usage amount of steel material. For instance, the usage amount of steel material by a 2300 MPa level steel strand is about 24% less than by an 1860 MPa level steel strand. Meanwhile, the increase of steel material strength would also simplify the pre-stressed structure and reduce the construction cost, which has significant economic and social benefits.
Chinese Patent Literature CN103122437A discloses a vanadium-silicon composite micro-alloyed super-high-strength coil rod and a preparation method thereof. This coil rod comprises 0.85%-0.95% of C, 0.95%-1.10% of Si, 0.50%-0.60% of Mn, 0.20%-0.35% of Cr, 0.01%405% of Ti, 0.005%4050% of Al and 0.11%-0.15% of V, as well as one or more selected from the group consisting of 0.001%-0.15% of Ni, 0.001%425% of Cu, 0.0001%4005% of B, 0.01%-0.03% of Nb and 0.001%-0.03% of Mo, with the remainder being Fe and impurities. The aforementioned coil rod has high strength with a tensile strength larger than 1370 MPa and can be used for producing 2140 MPa level pre-stressed steel strand. However, the aforementioned coil rod cannot meet the requirement of higher strength pre-stress, and it remains a research hotspot in the field of alloy to achieve preparation of higher strength pre-stressed steel strand.